FIG. 1 is a schematic diagram of a system architecture evolution (System Architecture Evolution, SAE for short) network architecture. As shown in FIG. 1, the SAE network architecture includes: an evolved UMTS terrestrial radio access network (Evolved UMTS Terrestrial Radio Access Network, E-UTRAN for short) that is used for implementing all wireless-related functions of an evolved network and may also be referred to as an E-UTRAN NodeB (E-UTRAN NodeB, eNodeB for short); a mobility management network element (Mobility Management Entity, MME for short) that is responsible for mobility management of a control plane, including management of a context and a mobility status of a user equipment (User Equipment, UE for short), allocation of a temporary user identity, and the like; a serving gateway (Serving Gateway, SGW for short) that is a user plane anchor between 3GPP access networks and is an interface for terminating a connection to the E-UTRAN; a packet data network gateway (Packet Data Network Gateway, PGW for short) that is a user plane anchor between a 3GPP access network and a non-3GPP access network and is an interface for terminating a connection to an external packet data network (Packet Data Network, PDN for short); a policy and charging rules function entity (Policy and Charging Rule Function, PCRF for short) that is used for policy control and decision and flow based charging control; a home subscriber server (Home Subscriber Server, HSS for short) that is used for storing user subscription information; a UMTS terrestrial radio access network (Terrestrial Radio Access Network, UTRAN for short) and a GSM/EDGE radio access network (GSM/EDGE Radio Access Network, GERAN for short) that are used for implementing all wireless-related functions in existing GPRS/UMTS networks, where the UTRAN includes a radio network controller (Radio Network Controller, RNC for short) network element and a base station (NodeB) network element, and the GERAN includes a base station controller (Base Station Controller, BSC for short) network element and a base station (Base Transceiver Station, BTS for short) network element; a serving general packet radio service support node (Serving GPRS Supporting Node, SGSN for short) that is used for implementing such functions in GPRS/UMTS networks as routing and forwarding, mobility management, session management, and user information storage; non-3GPP IP access networks (Non-3GPP IP Access) that are mainly some access networks defined by non-3GPP organizations, such as a wireless local area network (Wireless Local Area Network, WLAN for short), worldwide interoperability for microwave access network (Worldwide Interoperability for Microwave Access, Wimax for short), and code division multiple access network (Code Division Multiple Access, CDMA for short); and an authentication, authorization and accounting server (Authentication, Authorization and Accounting Server, AAA Server for short) that is used for performing access authentication, authorization and accounting functions on a UE.
In the foregoing existing SAE architecture, when a network element is reset due to a fault, a context of a UE stored in the network element is deleted, causing an interruption of an ongoing service of the UE after the network element recovers. To continue with the service, the UE has to re-register with a network and re-initiate the service. More seriously, the UE generally does not perceive the fault in the NE on a network side, and therefore, does not initiate a registration process to re-register with the network and re-initiate the service. Therefore, all services of the UE are actually unavailable.